RC Film Grain

Add noise to a render and you get texture - but it's flat texture. Real film grain isn't flat. It piles up in the shadows, thins out in the highlights, and reads differently on skin than on a bright sky. RC Film Grain is the node that understands this: it generates grain, then modulates that grain by the luminance of the image, so dark areas get more of it and bright areas stay cleaner. It's the difference between "I put a filter on this" and "this looks like it was shot on film."

It's one of the more grown-up nodes in the RC Image Compositor pack, with a control set that starts to feel like a real film emulation plugin rather than a noise generator.

How it works

Under the hood it's a two-layer operation. The node builds a grain layer, computes a luminance mask from the image, and uses that mask to scale how much grain lands in each tone. Then it blends the grain layer into the image with a Photoshop-style blend mode - overlay by default, with add, screen, soft_light, and linear_dodge as alternatives. Because the grain is a separate layer with its own blend math, you get natural-looking texture rather than a random-value paste.

The luminance_response slider is the heart of it: 0.0 gives uniform grain, 1.0 gives the realistic film curve (more in shadows, less in highlights), 2.0 pushes it to extremes. grain_midtone and highlight_protection are the fine-tuning handles - think of them like the midtone and black-point sliders on a Levels node, but controlling where grain lives instead of where tones clip.

The inputs that matter

• image - input tensor.
• intensity - overall grain strength (0–1). 0.15 default is tasteful; go higher for a gritty look.
• grain_size - 0.3 to 3. Smaller is finer. Bigger reads as coarse, chunky grain.
• luminance_response - the shadow/highlight grain distribution described above.
• monochrome - on (default) gives clean grayscale grain; off gives chromatic color grain like expired color film.
• blend_mode - overlay is your natural default; screen is softer; linear_dodge gets glowy.
• seed - set this for reproducible grain, so the same frame with the same seed gets the same texture. Important for video.

It outputs two things: the grained image, and a grain_map MASK showing where grain was applied - handy if you want to composite or inspect the effect.

How to install it

Part of the RC Image Compositor pack:

cd ComfyUI/custom_nodes
git clone https://github.com/kj863257/ComfyUI_RC_Image_Compositor
cd ComfyUI_RC_Image_Compositor
pip install -r requirements.txt

Restart ComfyUI, or search "RC Image Compositor" in ComfyUI Manager. Dependencies are light: pillow, numpy, opencv-python.

Common issues

The typical failure is dialing intensity to 0.4+ and wondering why everything looks like static. Real film grain is faint; if you want it to read, strengthen the shadow-side grain with luminance_response and grain_midtone instead of hammering the global intensity.

If you're doing video, set a fixed seed or your grain will shimmer between frames - that dancing static is the single most obvious tell of an AI-processed clip. And if your target image already has a baked-in denoise smoothness, run this after your color grade, not before, or the grade will smear the grain you just added.